Pen



FIG. 1 is a front elevational view of a pen showing my new design;

FIG. 2 is a top plan view;

FIG. 3 is a bottom plan view;

FIG. 4 is a right side elevational view, rotated 90° with respect to FIG. 1; and,

FIG. 5 is a perspective view of the pen. 

The ornamental design for a pen, as shown. 